sqlCacheDependency 更新缓存Cache

第一步

修改web,config

<!--定义数据库连接-->
 <connectionStrings>
  <add name="NorthwindConnectionString" connectionString="Server=USERRYRDB;Database=Northwind;UID=sa;pwd=密码" providerName="System.Data.SqlClient"/>
 </connectionStrings>
 <system.web>
    <!-- 定义缓存策略-->
  <caching>
   <sqlCacheDependency enabled="true" pollTime="10000">
    <databases>
          <!--
          name:必需的 String 属性。
              要添加到配置集合中的 SqlCacheDependencyDatabase 对象的名称。
              此名称用作 @ OutputCache 指令上 SqlDependency 属性的一部分。
          pollTime:设置 SqlCacheDependency 轮询数据库表以查看是否发生更改的频率（以毫秒计算）。这儿是一个测试,所以设为10秒,请加大此值
          -->
     <add connectionStringName="NorthwindConnectionString" name="Categories"/>
    </databases>
   </sqlCacheDependency>
  </caching>
 </system.web>

第二步.定义cachedData测试类

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Web.Caching;
using System.Data.SqlClient;

/// <summary>
/// Summary description for CachedData
/// </summary>
public class CachedData
{
    private string Key;
    private string _Source;
    /// <summary>
    /// 指示数据从哪儿读取的
    /// </summary>
    public string Source { get { return _Source; } }
 public CachedData()
 {
        Key = "Categories";
        _Source = "未知";
 }

    //读取数据
    public DataView getFromCache() {
        if (HttpRuntime.Cache[Key] == null)
        {
            //取数据
            SqlConnection conn = new SqlConnection();
            conn.ConnectionString = ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString;
            SqlCommand comm = new SqlCommand("SELECT [CategoryID], [CategoryName], [Description] FROM [Categories]", conn);
            SqlDataAdapter sda = new SqlDataAdapter(comm);
            DataSet ds = new DataSet();
            conn.Open();
            sda.Fill(ds);
            DataView dv = ds.Tables[0].DefaultView;
            conn.Close();

            //启用更改通知
            SqlCacheDependencyAdmin.EnableNotifications(ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString);
            //连接到 SQL Server 数据库并为 SqlCacheDependency 更改通知准备数据库表
            SqlCacheDependencyAdmin.EnableTableForNotifications(ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString, "Categories");
            //制定缓存策略
            SqlCacheDependency scd = new SqlCacheDependency("Categories", "Categories");
            //插入缓存
            HttpRuntime.Cache.Insert(Key, dv, scd);
            _Source = "Database";
            return dv;
        }
        else {
            //从缓存中取值
            _Source = "cache";
            return (DataView)HttpRuntime.Cache[Key];
           
        }
    }
}

这样就完成了。写个页面测试一下就行了。